Dry powder bleaching compositions



nited States .1

ABSTRACT OF THE DISCLOSURE Dry powder or granular bleaching compositions comprising an alkali metal salt of dichloroisocyanuric acid or a complex thereof in combination with pulled borax. The compositions are particularly suited for use in clothes washing machines.

BACKGROUND OF THE INVENTION This invention relates generally to bleaching compositions and more particularly to bleaching compositions in a dry powder or granular form which is especially suitable for use in clothes washing machines.

The major portion of household chlorine bleaching of clothes being washed in automatic clothes washing ma chines is presently accomplished with the use of liquid hypochlorite bleach. These liquid bleaches are sold to the consumer as dilute solutions of an alkali metal salt of hypochlorous acid; the most common being 5.25%6.0% solutions of sodium hypochlorite. These products are generally recommended for use at 1 cup per washerload, which results in approximately 200 parts per million of available chlorine per average 16 gallon capacity washer.

Although the aforesaid liquid bleaches are effective for their primarily intended purpose, there are a number of major disadvantages associated with their use. For example, they are inherently prone to chlorine volatilization from a container which has been opened, with attendant loss of bleaching strength, particularly when the container in which the liquid is packaged is not tightly closed during storage.

Also, direct contact of the compositions with clothes, prior to dilution in the wash water, can cause localized color fading and/or fiber damage to the clothes. In advertent, but nevertheless possible, splashing onto the skin or into the eyes of the user or others, can cause serious physical harm. Accidental spillage of the liquid compositions during use is inconvenient and obviously damaging to the environment.

In consideration of the foregoing disadvantages of the liquid bleaching compositions presently available, dry powder bleaching compositions have been developed and presently are also available commercially. These powdered bleaches contain an organic chlorine compound thereby offering the consumer another way to bleach clothes. The most common of these organic compounds present in the current powder bleaches are the alkali metal salts of dichloroisocyanuric acid. Such dry bleach products are usually made by mechanically post-blending the isocyanurate with a previously spray-dried detergent base. This sequential procedure is necessary, as otherwise the isocyanurate would be activated in the crutcher of the spraydrying operation if previously admixed with the detergent base, thereby to result in high loss of available chlorine.

In these known powdered bleach compositions, an inert base, such as the aforementioned spray-dried detergent Patented Nov. 3, 1970 base, is used to extend the isocyanurate so that the ultimate consumer can easily measure the prescribed dosage needed for effective bleaching. The point is that the amount of isocyanurate needed to deliver 200 p.p.m. chlorine per cup of composition is approximately 20.0 grams, more or less, depending on the bleaching compound, which amount corresponds volumetrically, to about 21 cc. It is, of course, inconvenient for the consumer to measure such small volumes of powder accurately from a box under the usual household laundry conditions. Hence, the consumer may inadvertently use many times the desired amount of bleaching agent, resulting in extensive fiber damage. However, the addition of filler offers a convenient means of utilizing measuring cups, or /2 cups, or any other convenient measuring units for introducing the compositions into the wash water. The fillers referred to above, can best be described as alkaline detergent builders and sequestering agents such as sodium tripolyphosphate, sodium carbonate, sodium silicate, tetrapotassiumpyrophosphate, sodium sulfate, sodium chloride, sodium metasilicate, compatible surface active agents and mixtures thereof to achieve a finished bulk density of 2040 pounds/ft. These materials are readily available commercially and lend themselves to the aforesaid spraydrying and post-blending operation for incorporation with the isocyanurate. Although the filler portion of the powdered bleach is necessary, it is known that under conditions of elevated temperature (130 F.) or moderately high temperature and high humidity F.90% Rel. Hum.) instability occurs resulting in high losses of available chlorine. Comparative data are furnished in Table D of Example I(D) infra to illustrate this disadvantage inherent in the compositions of the prior art and to demon strate the advantage in this area provided by the compositions of the present invention.

SUMMARY OF THE INVENTION With the above-noted disadvantages of the known chlorine-furnishing bleaching compositions in liquid or powder form in View, it is a primary object of the present invention to provide generally more stable powder bleaching compositions comprising a chlorine-providing component and a filler.

It is a further object of this invention to provide such generally more stable powdered bleaching compositions which have the desirable attribute of assuring consistent parity of bleaching performance with liquid hypochlorite bleaches in the common usage.

It is an additional object of the present invention to provide constancy of homogeneity of the mixtures of bleaching component and filler.

It is yet another object of the invention to provide said compositions .which have greater product stability under conditions of elevated temperature and/ or humidity.

Another object of the invention is to provide powdered bleaching compositions which aflord convenience and ease of use.

Another object of the invention is to provide said compositions which are relatively safe when inadvertently spilled.

Still another object of the invention is to provide said compositions which have the further attribute of rapid solubility when introduced into the wash water.

Yet another object of the invention is to provide compositions having the foregoing desirable attributes and which also lend themselves to comparatively facile preparation in commerical quantities.

Other objects and advantages of the invention will appear from the description thereof that follows.

Generally, the foregoing objects are obtained, in accordance with the present invention, by the provision of a powder bleaching composition comprising an isocyanurate in powder form selected from th group consisting of those having either of the following two formlae:

wherein M is an alkali metal selected from the group consisting of sodium and potassium; in combination with puffed borax in granular form. In the presently preferred compositions, the proportions by weight of the isocyanurate to the pufied borax ranges from about :85 to about 60.40; the major proportion of the particles of the isocyanurate and the puffed borax is of a size within the U.S. sieve range of from about 40 to about 100; and the bulk density of the total isocyanurate present is Within the range of from about 50 to about 65 pounds/ft. and that of the total puffed borax present is within the range of from about 3 to about 40 pounds/ft. In the more preferred forms of the compositions of the invention, the weight range of the isocyanurate to the puffed borax is within the range of from about :75 to about :55, more than 80% of the particles of the isocyanurate is within the U.S. sieve range of from about to about 200, and over 80% of the particles of the puffed borax are in the U.S. sieve range from about 40 to about 100. In the optimum compositions which have been found to provide the highest order of all of the aforesaid advantages of the compositions of the invention, the weight ratio of the isocyanurate to the puffed borax has been found to be about 30:70, with the particle size distributions of the isocyanurate and the puffed borax having the major proportions thereof within the aforesaid ranges and the total size distributions such as to give a bulk density of 56 pounds/ft. for the isocyanurate and a bulk density of 12.5 pounds/ft. for the puffed borax.

As appears from the foregoing, the present invention resides in the discovery that each of the two components of the powder bleaching compositions; i.e. the isocyanurate and the puffed borax, must have definite and specific physical characteristics to achieve an effective and stable product, which exhibits the desirable advantages referred to hereinbefore. The most critical of these properties is the bulk density of the puffed borax and the particle size distribution of both the isocyanurate and puffed borax.

The isocyanurates useful in the compositions of the invention are presently available commercially. For example, potassium dichlorocyanurate is available under the trade name ACL59 and [(monotrichloro)-tetra- (monopotassium dichloro)] penta-isocyanurate is available under the trade name ACL-66. Moreover, said cyanurates and others useful in the invention may be prepared in accordance with the methods set forth in U.S. Pat. 3,150,132.

The puffed borax useful in the preparation of the compositions of the invention is also available commercially in various bulk densities and particle size distributions, although extensive use of this material has up to now been nil. It is a form of borax made by the rapid heating of hydrates of sodium tetraborate. It is characterized by versatility of bulk density, large surface area, rapid solubility rate, and high absorptive potential for many substances.

For use in the compositions of the present invention, the puffed borax may be prepared by rapidly heating the pentahydrated form of borax in a hot air stream. Some of the water of hydration within the individual borax feed particles is flashed off, thereby resulting in a new particle of greater surface area and lower bulk density. By this method most densities of from about 3 to about 40 pounds per cubic foot are attainable from an original stock feed having a bulk density of 60-65 pounds per cubic foot. These resulting lower bulk densities are a function of the rate of the feed of the stock borax, the temperature to which the stock borax is exposed, and the residence time of the particles in the heating area. The finished product particle size distribution is dependent upon the desired bulk density of the puffed borax and the particle size distribution of the starting borax feed.

In the compositions of the invention, the selected isocyanurate and the puffed borax, each having the particle size distribution and bulk densities within the ranges set forth hereinabove, may be blended by suitable blending apparatus in weight ratios within the proportion ranges also set forth above, to result in the homogeneous products of the invention, which exhibit uniform chlorine distribution as well as the other advantages referred to hereinbefore.

The successful blending of materials of substantially equal particle size distributions and bulk densities normally poses no real processing problems, per se. However, the compositions of the present invention demonstrate that the successful blending of the two components with different particle size distributions and particularly bulk densities, results surprisingly in useful, more stable, effective consumer products highly suitable for use as a powder bleach in washing machines, only when there is made a choice of weight proportions, particle size distributions, and bulk densities for the two components, as set forth hereinbefore. Thus, preferably, the proportions by weight of the isocyanurate to the pufied borax ranges from about 15:85 to about 60:40; the major proportion of the particles of the isocyanurate and the puffed borax is of the size within the U.S. sieve range of from about 40 to about and the bulk density of the total isocyanurate present is within the range of from about 50 to about 65 pounds/ft. and that of the total puffed borax present is within the range from about 3 to about 40 pounds/ftfi.

Although excellent results have been obtained with compositions in accordance with the invention which consist essentially of the aforesaid two components; i.e., selected isocyanurate and puffed borax, various additives may be incorporated in minor proportions, as will appear to those skilled in this art. Thus, for example, such additives as suitable detergent builders, sequestering agents, compatable surface active agents, mineral oil, perfume, optical brighteners and/or stable colors for identification purposes, and the like, may be incorporated in the compositions in amount up to about 15% by weight of total composition.

As illustrative of formulations which provide powdered bleaching compositions having the aforesaid desired characteristics there are given below the following examples:

EXAMPLE I (A) Batches of potassium diclhorocyanurate and puffed borax were prepared which had the particle size distribution and bulk density respectively given in Table A below:

TABLE A Isocyanurate Pufied borax 100. 0 100. 0 Bulk density 1 56 1 12. 5

1 Pounds/ft.

Thirty parts by weight of the puffed borax were blended with 70 parts by weight of the isocyanurate in a laboratory twin shell blender to prepare five separate 1000 gram batches.

(B) The five batches obtained in (A) above were respectively designated I-V and after 15 minutes mixing time were separately analyzed for mesh size distribution with the results given in Table B below:

TABLE B ml. thiosulfateX N thiosulphateX 0.03545X 100 avallable chlorine: Wt. Sample The results of the determination of available chlorine in the M2 cup samples in accordance with the foregoing analytic procedure are given in Table D below:

15 m'nutes mixin 10 1 g] TABLE D Percent retained B t h %egp Sample Perlcefit ac I II III 1 en Wei avaia e IV V Average Box No. identification cation g g. chlorine Mesh size:

3 g 2 .4 99. 2 9 99 9 99 9 99 8 10 34.4 23.3 1 34.3 23.1 2 35.2 23.2 (C) Each of the aforesaid batches after the minutes 2 32-5 5 mixlng time described in (B) above were then subjected 9 3313 5311 to a one hour shaking period on standard shaking apparagig 4 tus. The surprising stability of the compositions with 4 35.7 23:; respect to homogeneity appears from the comparison of g the compositions given in Table C below: 2 5 20: 2 g 33.3 23.2 2.8 2 .2 [15 minutes m TABIIE C h h 8 34A ixing p us one our s akrng] 10 33. 7 20. 9 P 4 29.2 19.3 ercent retained 5 32. 9 20. 3 6 30. 20.0 Batch I II III IV V Average 7 33.2 22.5 Mesh size: 8 35' 8 22' 8 .3 .4 2.6 2.6 38 23.0 20.1 19.3 19.6 20.5 EXAMPLE H +2001", 31 312 31g 3:; Separate batches of potassium dichlorocyanurate, so- -200 4.3 4.3 5.2 5.1 4.5 dium dichlorocyanurate, the trichloroisocyanurate com- 5 9&2 998 996 plex (i.e., [(mono-trichloro)-tetra-(monopotassium-di- (D) Utilizing the materials and blending process described in (A) above, a limited plant run was performed utilizing plant equipment to obtain the dry powder bleach composition in amount suflicient to fill two dozen 20 ounce boxes. Six of said boxes were selected at random. Thereafter, consecutive /2 cup samples were taken from each of said six boxes and certain of these samples, which were selected with the use of a table of random numbers, were subjected to the analytical method for determination of available chlorine, described below:

Procedure for the Determination of Available Chlorine The determination of available chlorine in formulated products containing chlorinated cyanuric acid and derivatives thereof may be performed generally by means of an iodometric titration with sodium thiosulfate to a starch end-point. In the specific procedure used, the calculated amount of sample for an approximate 40 ml. sodium thiosulfate titration is weighed onto a glassine weighing paper on an analytical balance. The sample is then transferred to a 500 ml. Erlenmeyer flask containing 250 m1. of 3% potassium iodide solution. The weighing paper and the walls of the flask are rinsed with distilled water. A stirring bar covered with Teflon is added to the flask and the latter is placed on a magnetic stirrer. Stirring is continued until solution has been effected (usually in from 3-5 minutes). Approximately gm. of crushed ice is added and then 25 ml. of 1: 1 sulfuric acid. The resulting solution is titrated with 0.1 N standard sodium thiosolfate to a light yellow color, while the contents of the flask are continually stirred. Starch indicator solution is then added in amount to give a deep purple color to the solution, and titration is continued slowly until the color just disappears. The volume of sodium thiouslfate solution used is recorded, and the chloro)] penta-isocyanuate, obtainable commercially as (ACL-66), and the puffed borax were prepared from material having the particle size distribution given in Table E below:

TAB LE E Percent retained Potassium (or sodium) Trichloroiso- Pufted U.S. Sieve N0. dichlorocyanurate cyanurate corn. borax Ingredient Percent by weight K (or Na) dichloroisoeyanurata. 33.0 30.0 25.0 Trichloro isocyanurate complex. 31. 0 28. 0 25. 0 Pufiedborax 67.0 70. 0 75.0 69.0 72. 0 75.0

As appears from the foregoing, the percent of available chlorine provided by the randomly selected half-cup samples taken from the randomly selected boxes which were prepared under plant operating conditions was surprisingly constant.

EXAMPLE III (A) Utilizing the materials and blending procedure of Example II above, compositions having the respective TAB LE G Percent by weight Ingredient i ii iii i;

K diehloroisoeyanurate (ASL-50) 30 30 Triehloroisoeyanurate complex (ACL- Mineral oil. Spray-dried detergent base (B) Three gram samples of each of the formulations i-iv respectively of Table G above, were set up in closed four ounce square bottles. The twelve bottles Were placed in an oven which was maintained at 45 C. for two weeks. During that time a sample of each of the formulations i-iv was withdrawn on the 5th, 8th and 14th day of the two week period and subjected to determinations with respect to loss of percent of available chlorine. The results of said determinations are given in Table H below TABLE 11 Percent available chlorine loss Formulation identification 5 days 8 days 14 days The superiority of the compositions of the invention with respect to retention of bleaching capability after subjection to prolonged adverse heat conditions is apparent from the foregoing.

(C) Three 20 gram samples of each of the formulations i-iv respectively of Table H above, were in this instance, set up in open Petri dishes. The twelve bottles were stored in an autoclave maintained at 90 F., 85 Rel. Hum., for two weeks. During that time samples of each of the formulations i-iv were again withdrawn at the 5, 8 and 14 day intervals and subjected to determinations (1) an isocyanurate in powder form selected from the group consisting of:

(a) those having either of the following two wherein M is an alkali metal selected from the group consisting of sodium and potassium; and

(b) mixtures thereof; and

(2) pufred borax in powder form; in which composition:

the bulk density of the total isocyanurate present is within the range from about 50 to about 65 p0unds/ft.

the proportions by weight of said isocyanurate to said puffed borax are in the range of from about 15:85 to about 60:40;

the puffed borax has a bulk density of from 3 to 40 pounds/ft. and

over 80% 0f the particles of said puffed borax are in the U.S. sieve range of from about 40 to about 100.

2. A powder bleaching composition as defined in claim 1, wherein the weight ratio of said isocyanurate to said pulfed borax is in the range of from about :55 to about 25:75; and more than 80% of the particles of said isocyanurate are in said U.S. sieve range of from about to about 200.

3. A powder bleaching composition as defined in claim 1, wherein the weight ratio of said isocyanurate to said puflfed borax is about 30:70; and the total particle size distributions of said isocyanurate and said puffed borax are such as to give a bulk density of 56 pounds/ft. for said isocyanurate and a bulk density of 12.5 pounds/ft. for said pulfed borax.

4. A powder bleaching composition as defined in claim 2, wherein the total particle size distribution of said isocyanurate and said puffed borax are as given below:

with respect to loss of percent available chlorine as in (B) above. The results of these later determinations are Sieve lsocyanmate Pufied borax given in Table I below:

0.0-1.0 0. 0-4.0 TABLE I 33.0 0. 4-130 .0 30. 0. Percent available chlorine loss 40.056.0 16. 12.0-29.0 1. 0-3.0 Formulation identification 5 days 8 days 14 days 0 15 0 O 0 27 32 32 24 29 31 2O 26 30 References Cited 83 98 UNITED STATES PATENTS Here again the superior stability of the compositions of the invention under adverse conditions is manifest.

We claim:

1. A powder bleaching composition consisting essentially of:

3,154,494 10/1964 Speak et a1. 252-99 XR MAYER WEINBLATI, Primary Examiner U.S. Cl. X.R. 252-187 3 3? UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,53 5 Dated November 3, 97

Invent0r(s) Bernard Weinstein and. Herman L. Marder It: is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In column 1, line 45, In ad-" should read -Ina.d- In column L, line 60, diclhorocyanurafioe should read -dichlorocyanurate--. In column 8, line L3, (claim t) "distribution" should read -distributions-; and in line 48, (claim in the table, under the headin Q "Puffed Borax", "OAT-15.0" should read L.O-l5.O--.

SIG-1M3) MD SEALED b-'19 1971 M In Edam-dbl. A mm 2. w: m. Am Officer Manner of Patents 

